Plasticized compositions based on polyvinylchloride (PVC) are widely used in the floor-covering industry because of the properties of high scratch resistance and smooth surface finish which such compositions provide. These PVC-containing compositions are well known in the art, being disclosed for example in U.S. Pat. No. 3,761,555, U.S. Pat. No. 4,888,145 and U.S. Pat. No. 4,923,658. However, the PVC-containing compositions have the substantial disadvantage of releasing hydrogen chloride and possibly other toxic chemicals when burned. As environmental regulations become more restrictive and the need for recycling becomes more significant, alternatives to PVC-based compositions become more desirable.
These alternate compositions must demonstrate the good surface properties of the PVC-based compositions to be acceptable to industry and should be able to be calendared with the same equipment used for PVC compositions. One example of a PVC-free formulation for floor and wall coverings is disclosed by European Patent Application 321760. The formulation is a homogeneous synthetic material comprising (1) an ethylene-vinyl acetate copolymer optionally employed with propylene with minor amounts of ethylene-propylene-diene monomer terpolymer and polyethylene, (2) a filler material, (3) a coloring agent and optionally (4) minor amounts of conventional additives. These formulations suffer from stiffness and the poor processability and the high density thereof restricts the application of the formulations as wall coverings.
A second PVC-free composition is disclosed by Japanese Patent Application No. 60-034682. The composition, useful for floor coverings, is prepared by adding a minor amount of a homopolymer or copolymer of isobutylene to a crosslinkable rubber and/or a thermoplastic rubbery polymer. The blend is subsequently vulcanized through use of a crosslinking agent. The composition is in the form of a three-dimensional network and floor material prepared from the composition is hard and difficult to process.
It would be of advantage to have polymer compositions not based on polyvinylchloride which demonstrate low density and good processability and the scratch resistance and good surface appearance properties of PVC-based compositions, but which are environmentally more acceptable.